Thanks for the props. I might have another solution for you (again... it's what I do and it works well for me... I also manage my own DNS, though - you may be able to do something like this with zoneedit.com.)

Open a regular dyndns.org account and have your Linksys keep it updated. I take my own domain and add a subdomain (vpn.mydomain.com) and set that up as a cname that points to xxx.dyndns.org. It's not totally seamless... people can see that vpn.mydomain.com is a cname that points to xxx.dyndns.org, but it is a heck of a lot more slick than publishing your official address as a dyndns.org address.

Remember to create a new security certificate for vpn.mydomain.com to avoid those certificate errors.

"Custom DynDNS" is a paid service offered by DynDNS. It indeed can be updated like xlr8 said. Using the xlr8 method, the dynamic DNS service doesn't even need to be DyDNS, the vpn.mydomain.com hosted on DYNDNS can point to xxxx.anyolddns.com ... and it works.

I believe spaminacan uses "Dyndns" generically, and he's asking for a customizable dynamic DNS client that can be scripted to talk to the aforementioned anyolddns.com , and all others .... Some open source images have that. That indeed can come in handy. Some countries have blocked dyndns.org. And there may be other reasons not to use dyndns.org, despite it being the most rock steady and earthquake proof dynamic DNS service in the universe.

I am using the paid Dyndns. Currently I am using a client from inside my network that is based off a workstation. I would love to have the client come from my RVL200. I just need to find a linux client that works with custom dyndns and re-compile it. I just need the documentation on how to do it.